Your own source says it "has been adopted by many other police departments across the English-speaking world" and has "been adopted by so many police departments, in fact, that it's practically a Stock Phrase in the English-speaking world."

And even if that's not true (since I'd hardly call TVTropes an authoritative source), I was using it rhetorically. I should think that regardless of its origin, that motto closely represents the ideal that we want our police agencies to uphold.